Felting needle is fit on the needle machines or needle looms, it has many kinds of different types.
Generally, we have the gauge of 40,38,36,32, or 30,25.
The total length of felting needle is usually chosen as 3 inch and 3.5inch. Working part length is usually chosen as 24mm and 30mm, that is include the taper length.
And the barb spacing between barbs is often chosen R and C. The point is often chosen R and C.